Matrix-addressed, flat-panel displays are rapidly gaining acceptance as computer terminal displays and instrument displays in automobiles and aircraft cockpits. In order to compete with cathode ray tubes in more than limited applications, flat-panel displays must be offered in full color. Full-color displays require the use and control of the three primary colors; red, blue and green. Flat-panel displays are matrix-addressed, i.e., a set of row electrodes and a set of column electrodes with a picture element located at each intersection of row and column electrodes. Construction of a color display requires that red, green, and blue picture elements (dots) be superimposed or placed in close proximity and be small enough so that the human eye integrates rather than resolves the individual color dots.
To date, prior designs for full-color displays consist of the coplanar (single-layer) design or the stacked (threelayer) design. In the coplanar design, the three phosphors are placed side-by-side to form one picture element. This requires electrodes that are one-third the width of the picture element, which conflicts with the design goal of lower electrode resistance. The wider the electrode width, the lower the electrode resistance and the greater the brightness. However, as the brightness goes up, the picture resolution decreases as each picture element gets larger.
In the stacked design, the three color phosphors are placed one on top of the other to form one picture element. In thin-film electroluminescent displays, the phosphor layers and the electrode layers must be separated from each other by layers of insulating material, giving the stacked display a minimum of sixteen layers. The reflection and loss of transmission at each layer interface decreases the contrast ratio of the display. Furthermore, the stacked design has a set of row and a set of column electrodes that are separated by only one insulating layer, thereby creating undesirable capacitance.
Accordingly, an object of the present invention is a full-color, flat-panel, electroluminescent display capable of high brightness and high resolution.
A further object of the present invention is a flatpanel display design requiring a minimum of layers thereby increasing the contrast ratio.
A still further object of the present invention is a flat-panel display design whose layered structure decreases undesirable capacitance between row and column electrodes.
Other objects and advantages of this invention will become more apparent hereinafter in the specification and drawings.